Angled Engines - Physics 101 question

[jbdenney]

I have 4 Thuds mounted on 4 outrigger tanks. Each Thud puts out 120kn thrust.

Now in situation 1 they are all mounted pointing straight back. That means all of the thrust of each engine is pushing the same direction making a total of 480kn thrust.

Situation 2 - all 4 Thuds are angled out by 45 degrees. By basic physics each engine SHOULD be pushing straight back with 70kn each and 70kn each pushing toward the center of the rocket. The sideways thrust should cancel each other out leaving 0kn lateral force and 280kn pushing forward. But when I look at the Delta-V info stack it shows 480 total thrust. Is this forward thrust or is this just the total thrust without accounting for the thrust vectors?

Are the angled engines giving me Kerbal Physics 480kn forward thrust or am I getting Collage Physics of 280kn of forward thrust and 280kn of wasted acceleration?

Thanks in advance

Bruce

[Rhomphaia]

The thrust values for the stock DeltaV panels dont care about direction. just displaying the total thrust, the TWR indicator doesn't seem to care about it either.  but the DeltaV indicator does.

Also 45degrees give the thud 84.9kN forward by my working out from dimly remembered high-school maths, don't know what they are teaching in college physics

Edited May 20, 2020 by Rhomphaia

[jbdenney]

I managed to answer my own question by building a small test rocket and comparing AP for different configurations.

You are correct with 85.9kN. I was visualizing in my head that 45 degrees was halfway between 0 and 90 so I split the force in half. I forgot that it is "Force times sin(45)" or "Force times cos(45)" depending if you are talking about the X axis or Y axis relative to the angle. At 45 degrees the sin is equal to the cos so the x axis force is equal to the y axis force.

I took collage physics in 1975 so it has been a while.

 

Bruce